<!DOCTYPE html>
<html>
  <head>
    <title>IOT LAO WANG</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" type="text/css" href="stylesheet.css">
  </head>
  <body>
    <h1>Window pop test</h1>
    <p><button onclick="trige_waring()">Don't clike me</button></p>
    <script>
      function trige_waring() {
        var a = "Oh, This is a waring";
        window.alert(a);
      }
    </script>
  </body>
</html>